Diffusing film and liquid crystal display element employing the same

ABSTRACT

This invention is to provide a diffusing film, a lighting unit, and a liquid crystal display element which can efficiently uses a light from a light source and which can obtain a beautiful image. 
     A diffusing film comprising a powder which diffuses an incident light and which has an interference color of the same wave range with an absorption wave range, in uniformly and a diffusing film comprising two or more of a powder whose interference colors are complementary to each other, and a liquid crystal display element using the same.

This application claims the priority of Japanese Patent Application No.Heisei 8-215523, filed Jul. 26, 1996, Japanese Patent Application No.Heisei 9-98528, filed Mar. 31, 1997, Japanese Patent Application No.Heisei 9-98529, filed Mar. 31, 1997, and Japanese Patent Application No.Heisei 9-98532, filed Mar. 31, 1997 which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a diffusing film and a liquid crystaldisplay element, and in particular, relates to an improvement of itscolor tone.

BACKGROUND ART

In recent years, a liquid crystal display element is used in variousfields, and in particular, is largely used in a field of electronicindustries such as a notebook personal computer, portable liquid crystaltelevision, and the like, since the liquid crystal display element isthin-type and lightweight. This liquid crystal display element indicatesimage by controlling light transmission/shielding from an external lightor back lighting (internal light source) by means of a liquid crystalshutter, since the liquid crystal display element does not emit light initself unlike a plasma display. Namely, in a liquid crystal displayelement, a diffusing film, which is to provide a light in uniformly toan entire liquid crystal panel, is inserted into the backside of aliquid crystal panel in general. A reflective film that has highdiffused reflectance is used in the liquid crystal display which uses anexternal light. The reflective film scatters and reflects the externallight which is entered from the obverse side of the liquid crystal paneland returns to the liquid crystal panel. The display indicates image bycontrolling transmission/shielding by means of a liquid crystal shutter.While a diffusing film that has high diffused transmittance is used inthe liquid crystal display which uses a back lighting. The diffusingfilm diffuses and transmits the internal light from the reverse side ofa liquid crystal panel and provides a light to the liquid crystal panel.Transmission/shielding of light is controlled by means of the liquidcrystal shutter. Further, a semitransmissive diffusing film whichproperly uses the external light and the back lighting according toON/OFF of the back lighting, also can be used.

Conventionally, as for a technique regarding a transmissive diffusingfilm which diffuses a light flux from a back lighting, the techniquementioned in Japanese Unexamined Patent Publication No. Sho 57-88401 isknown. Also, as for a technique for complementing a color tone, thetechnique mentioned in Japanese Unexamined Patent Publication No. Sho60- 250382 is known.

A transmissive diffusing film mentioned in said Japanese UnexaminedPatent Publication No. Sho 57-88401 comprises one pearly pigment anddiffuses a light flux from a back lighting by this pearly pigment.

On the other hand, in addition to said pearly pigment, a polarizerdisclosed in said Japanese Unexamined Patent Publication No. Sho60-250382 further comprises fluorescent dye, blue dye and the like. Acolor tone is obtained by absorbing an optical component which has aspecific wavelength among a light flux from the back lighting, to dye.

However, the light transmittance in the case where white light wasentered, was low in short wave range as compared with long wave range,in the diffusing film mentioned in said Japanese Unexamined PatentPublication No. Sho 57-88401, as shown in FIG. 1a. Therefore, a colortone of a transmitted light in a diffusing film became dark liver brownand satisfactory color tone and lightness could not be obtained evenwhen this diffusing film was used for a liquid crystal display element.

Also, a polarizing film mentioned in said Japanese Unexamined PatentPublication No. Sho 60-250382 is exemplified as for a technique tocomplement an inferiority of color tone. However, an incident light froma back lighting was not effectively used since an optical componentwhich has a specific wavelength among the incident light from the backlighting was absorbed by dye. Accordingly, satisfactory color tone andbrightness could not be obtained even in the case where these dyes wereused in the diffusing film. Also, in view of the stability of colortone, satisfactory diffusing film were not obtained because dyes wereeasily deteriorated by light.

A semitransmissive liquid crystal display element which uses an externallight or an internal light according to well-lighted time or darkenedtime, spent lower power than a transmissive liquid crystal displayelement which continuously uses a light flux from an internal lightsource.

A semitransmissive liquid crystal display element needs to have lighttransmittance that a semitransmissive diffusing film which was locatedbetween a liquid crystal panel and an internal light source, uniformlydiffuses a light flux from the internal light source when the internallight source was switched ON and light reflectance that thesemitransmissive diffusing film uniformly diffuses the light fluxentered from an external portion to the liquid crystal display elementand reflects again to an external direction when the internal lightsource was switched OFF.

As for a technique to obtain a transmitted light and a reflected lightby white light in the case where white light is entered to asemitransmissive diffusing film, the technique mentioned in JapaneseUnexamined Patent Publication No. Hei 8-179125 is exemplified.

A semitransmissive diffusing film mentioned in said Japanese UnexaminedPatent Publication No. Hei 8-179125 uses one white pearly pigment in asubstrate. Namely, white transmitted and reflected light in thesemitransmissive diffusing film are obtained by whitening the pearlypigment in itself.

However, in the case where white light was entered to thesemitransmissive diffusing film mentioned in said Japanese UnexaminedPatent Publication No. Hei 8-179125, for example, the transmitted lightbecame dark liver brown, since light transmittance in thesemitransmissive diffusing film was low, as like the transmissivediffusing film, in short wave range as compared with long wave range asshown in FIG. 1. Therefore, satisfactory color tone and brightness couldnot be obtained.

Accordingly, though this semitransmissive diffusing film was used in alighting unit or semitransmissive liquid crystal display element,satisfactory color tone and brightness were not obtained nevertheless.

Further, the more labor-saving power is required in the case where aliquid crystal display element is used as portable type or on-vehicletype liquid crystal display element. In particular, downsizing andlightening of a portable apparatus becomes necessary with rapid spreadof portable use such as a portable telephone, a personal digitalassistants (PDA), and the like. Therefore, a reflective liquid crystaldisplay element which uses an external light without using a lightingunit (back lighting unit) which occupies a large part of electricityconsumption, is expected.

A conventional reflective liquid crystal display element was ablack-white display. A metal deposited film, a polishing metal plate,and the like which has metallic luster were used as a reflective film.Also, a semitransmissive diffusing film mentioned in Japanese UnexaminedPatent Publication No. Hei 8-179125 which has the same reflectivity as areflective film in spite of a semitransmissive diffusing film, wasexemplified.

However, said conventional reflective film which has metallic lustersometimes caused a so-called greasiness that luminance was extremelydecreased excluding a specular reflection angle, though said reflectivefilm had high specular reflection luminance. In the case where thisreflective film was used in a liquid crystal display element, visibilitywas sometimes spoiled.

Also, a semitransmissive diffusing film disclosed in said JapaneseUnexamined Patent Publication No. Hei 8-179125 uses one white pearlypigment in a substrate. Namely, white reflected light in thesemitransmissive diffusing film was obtained by whitening the pearlypigment in itself.

However, when white light was entered to a reflective film in the casewhere one of this white pearly pigment was used in a reflective film,there was a fear that the light reflectance at the reflective filmbecame low in long wave range in comparison with in short wave range.Accordingly, satisfactory color tone and brightness were not obtainedeven when these reflective films were used in the reflective liquidcrystal display element.

DISCLOSURE OF INVENTION

In view of the foregoing problems of the prior art, an object of thepresent invention is to provide a diffusing film and a liquid crystaldisplay which can efficiently use a light from a light source and whichcan obtain beautiful image.

To attain the above-mentioned object, a diffusing film of the presentinvention comprising a powder which diffuses an incident light and whichhas an interference light of the same wave range with an absorption waverange of the incident light, in uniformly.

Also, in said diffusing film, it is preferable to comprise two or moreof powder that each interference color is in a complementary relation.

Also, in said diffusing film, it is preferable to add 10% to 90% of apowder whose interference color is in a complementary relation withrespect to the other powder so as to obtain white transmitted light inthe diffusing film.

Also, in said diffusing film, it is preferable that said powder is apearly pigment.

Also, in said diffusing film, it is preferable that said powder istitanium dioxide coated mica which is coated titanium dioxide on thesurface of mica, and the layer thickness of titanium dioxide which iscoated on the surface of mica is the layer thickness that aninterference color of the same wave range with an absorption wave rangeof said titanium dioxide coated mica can be obtained.

Also, in said diffusing film, it is preferable that said powder istitanium dioxide coated synthetic mica which is coated titanium dioxideon the surface of synthetic mica.

Also, in said diffusing film, it is preferable that an amount of saidpowder is 0.01 g/m² to 100 g/m² in the case where said powder is set ona substrate.

Also, in said diffusing film, it is preferable that an amount of saidpowder is 1 wt % to 70 wt % in the case where said powder is set in asubstrate.

Also, a liquid crystal display element in the present inventioncomprising a diffusing film which diffuses a light and which uniformlycomprises a powder that an interference light of the same wave rangewith an absorption wave range of the light and a liquid crystal panelwhich controls light transmittance of a light flux from said diffusingfilm by changing a voltage which applies onto a liquid crystal layer.

Also, in said liquid crystal display element, it is preferable that saiddiffusing film comprises two or more of a powder whose interferencecolors are complementary to each other.

Also, in said liquid crystal display element, it is preferable that saiddiffusing film is a semitransmissive diffusing film and uses a powderwhich can generate a colored interference light. Also it is preferablethat said diffusing film tone a color tone at transmissive andreflective mode.

Also, said semitransmissive liquid crystal display element comprising:an internal light source which irradiates a light flux in the case wherethe internal light source is switched ON and which stops an irradiationof the light flux in the case where the internal light source isswitched OFF; a semitransmissive diffusing film which transmits thelight flux from said internal light source in the case where said lightinternal light source is switched ON and which reflects an externallight from a reverse side of said internal light source in the casewhere said internal light is switched OFF; and a liquid crystal panelwhich controls light transmittance of said light flux by changing avoltage which applies onto a liquid crystal layer, wherein saidsemitransmissive diffusing film comprises a powder which has a coloredinterference color.

A liquid crystal panel mentioned in here will be explained. For example,vibration direction of a light flux was changed with the change of theorientation of liquid crystal molecular, when a voltage was applied ontoa liquid crystal layer which was held between two alignment film. Amongthe light flux passed the latter alignment film, an polarizing filmwhich passed linearly polarized light of the prescribed vibrationdirection. The liquid crystal panel can control light transmittance bychanging a voltage which applies onto a liquid crystal layer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory view of an example of light transmittancespectrum of the conventional transmissive diffusing film.

FIG. 2 is an explanatory view of an example of light reflectancespectrum of the conventional reflective diffusing film.

FIG. 3 is an explanatory view of a powder which is used in a diffusingfilm of the present invention.

FIG. 4 is an explanatory view of interference light generating action ofthe powder shown in said FIG. 3.

FIG. 5 is an explanatory view of a liquid crystal display element usinga diffusing film in accordance with one embodiment of the presentinvention.

FIG. 6 is an explanatory view of display mechanism of the liquid crystaldisplay element shown in said FIG. 5.

FIG. 7 is an explanatory view of action of a powder used in a diffusingfilm in accordance with one embodiment of the present invention.

FIG. 8 is a comparative explanatory view of light transmittance in thecases where a diffusing film in accordance with one example of thepresent invention and the conventional diffusing film were used.

FIG. 9 is an explanatory view of light transmittance spectrum in thecase where the percentages of two titanium dioxide coated mica werevariously changed in the diffusing film of the present invention.

FIG. 10 is an explanatory view of light transmittance spectrum in thecase where the percentages of titanium dioxide coated mica and whitepigment were variously changed in the diffusing film of the presentinvention.

FIG. 11 is an explanatory view of light transmittance spectrum in thecase where the percentages of two titanium dioxide coated mica werevariously changed in the diffusing film of the present invention.

FIG. 12 is an explanatory view of reflective interference lightgenerating condition of a semitransmissive diffusing film in accordancewith the present invention.

FIG. 13 is a comparative explanatory view of light transmittancespectrum in the cases where the semitransmissive diffusing film inaccordance with the present invention and the conventionalsemitransmissive diffusing film were used.

FIG. 14 is a comparative explanatory view of light reflectance spectrumin the cases where the semitransmissive diffusing film in accordancewith one example of the present invention and the conventionalsemitransmissive diffusing film or reflective film were used.

FIG. 15 is a comparative explanatory view of light transmittancespectrum in the case where the percentages of two titanium dioxidecoated mica which were used in the semitransmissive diffusing film inaccordance with one example of the present invention were variouslychanged.

FIG. 16 is a comparative explanatory view of light reflectance spectrumin the case where the percentages of two titanium dioxide coated micawhich were used in the semitransmissive diffusing film in accordancewith one example of the present invention were variously changed.

FIG. 17 is a comparative explanatory view of light reflectance spectrumin the case where the percentages of two titanium dioxide coated micawhich were used in the semitransmissive diffusing film in accordancewith one example of the present invention were variously changed.

FIG. 18 is a comparative explanatory view of light transmittancespectrum in the case where the percentages of two titanium dioxidecoated mica which were used in the semitransmissive diffusing film inaccordance with one example of the present invention were variouslychanged.

FIG. 19 is a comparative explanatory view of light reflectance spectrumin the case where the percentage of two titanium dioxide coated micawhich were used in the semitransmissive diffusing film in accordancewith one example of the present invention were variously changed.

FIG. 20 is a comparative explanatory view of light reflectance spectrumin the cases where the reflective diffusing film in accordance with oneexample of the present invention and the conventional reflective filmwere used.

FIG. 21 is a comparative explanatory view of light reflectance spectrumin the case where the percentages of two titanium dioxide coated micawhich were used in the reflective diffusing film in accordance with oneexample of the present invention were variously changed.

FIG. 22 is a comparative explanatory view of light reflectance spectrumin the case where the percentages of two titanium dioxide coated micawhich were used in the reflective diffusing film in accordance with oneexample of the present invention were variously changed.

BEST MODE FOR CARRYING OUT THE INVENTION

As described above, a powder which has an interference light whose waverange is the same with an absorption wave range is used uniformly in adiffusing film in accordance with the present invention. Therefore, adiffused light at the diffusing film can be obtained as whiteinterference light in the case where white light enters into diffusingfilm, because an optical component which has specific wave range to beabsorbed by the powder and the like, can be favorably complemented bythe interference color of the powder.

Also, in the diffusing film of the present invention, two or morepowders that have interference colors in a complementary relation wereused in the place of said powder. Therefore, a diffused light at thediffusing film can be obtained with more white interference light, sincethe interference color of these powders can be favorably blended.

Also in said reflective diffusing film, a diffused light at thediffusing film can be obtained with satisfactory white interferencelight by adding 10% to 90% of the powder whose interference color is ina complementary relation, with respect to the other powder.

Also, a transmitted light at the diffusing film can be obtained withmore white interference light in the case where said powder is titaniumdioxide coated mica which is coated titanium dioxide on the surface ofmica and a layer thickness of titanium dioxide which is coated on thesurface of mica is determined as the layer thickness which can obtain aninterference color whose wave range is the same with an opticalcomponent which has specific wavelength absorbed by this titaniumdioxide coated mica.

Also, it is preferable that an amount of said powder is 0.01 g/m² to 100g/m² in the case where said powder is set on a substrate. On the otherhand, it is preferable that an amount of said powder is 1 wt % to 70 wt% in the case where said powder is set in a substrate. Namely, lightdiffusibility and light transmittance or reflectance of the diffusingfilm can be favorably controlled by determining the percentage of saidpowder.

According to the liquid crystal display element in accordance with thepresent invention, beautiful image can be obtained because a light froma light source can be efficiently used by using a diffusing film of thepresent invention in a lighting unit and a liquid crystal displayelement.

First, a powder which is characteristic in the present invention and hasan interference light of the same wavelength with an optical componentwhich has a specific wavelength absorbed by the powder is typified asshown in FIG. 3.

In FIG. 3, mica 10 is scaly and titanium dioxide 12 is coated onto micaand is surrounding mica in a thin-layer state.

Such titanium dioxide coated mica 14 (powder) has an interference colorof various color tones.

In the case where titanium dioxide coated mica 14 receives white light16, one part of the light is reflected on the boundary of a substrate18-titanium dioxide 12 and on the boundary of titanium dioxide 12-mica10.

As a result, a light which have some wavelength was not observed inappearance and a light which have other wavelength is amplified, in thecase where a reflected light 20 and 22 were observed. Namely, in view ofoptical path difference L (=almost twice of the layer thickness oftitanium dioxide), the top portion of the optical component of thereflected light 22 is located on the bottom portion of the opticalcomponent of the reflected light 20 in the optical component which hasthe wavelength of the reflected light 22 as shown in FIG. 4(A) and theoptical component which has the wavelength of the reflected light 20.So, both optical components are weaken each other and are externallydisappeared as shown in FIG. 4(C). However, in the case where theoptical component is half wave of FIG. 4(A) as shown in FIG. 4(D), eachof the optical component of the reflected light 20 and 22 shift for onewavelength. Both the top portion and the bottom portion overlap eachother and the amplitude is amplified as shown in FIG. 4(F).

For example, in the case where a reflected interference light 23generated by the reflected light 20 and 22, an interference color ofvarious colors such as red, violet, blue, green, and the like can beobtained by changing the layer thickness of titanium dioxide 12.

On the other hand, a part of white light 16 (incident light) became atransmitted light 24, since the light transmittance of titanium dioxide12 and mica 10 were high in the case where titanium dioxide coated mica14 was used. This transmitted light 24 was in a complementary relationwith said reflected interference light 23.

Accordingly, the transmitted light 24 can be obtained in variousinterference colors such as green, pale yellow, yellow, red, and thelike.

In this embodiment, optical layer thickness of titanium dioxide 12 wasconstructed so as to obtain the interference light 23 which has the samewavelength with the optical component which has specific wavelengthabsorbed by titanium dioxide coated mica 14. Therefore, the color toneabsorbed by titanium dioxide coated mica 14 can be complemented by theinterference color of the titanium dioxide coated mica 14.

For example, in the case where titanium dioxide coated mica 14 of thisembodiment absorbs blue optical component, the layer thickness oftitanium dioxide 12 which is coated on the surface of mica 14 isdetermined so as to obtain blue interference color. Also, the layerthickness of titanium dioxide is determined so as that the transmittedlight at the diffusing film can be obtained white interference color asa whole in the case where white light enters the diffusing film.

As for the powder of this embodiment which is typified by titaniumdioxide coated mica 14, titanium dioxide coated mica that titaniumdioxide was coated on scaly mica, fish scale guanine, basic white leadcarbonate, bismuth trichloride, and the like can be used.

Also, the layer thickness of titanium dioxide has extremely importantmeaning in these powders. The transmitted light had strong tendency tobecome slight yellow and was colored in the case where geometric layerthickness of titanium dioxide was less than 40 μm.

On the other hand, when the layer thickness of titanium dioxide was 40nm or more, a color appearance of transmitted light which is similar tothe interference color can be obtained. The interference colors of gold,red, violet, blue or green were displayed as a concrete products and thetransmission of light color appearance was similar to the interferencecolor.

Namely, a reflected interference lights 23 of pale gold, gold, red,violet, blue, and green interference color were obtained in the casewhere the layer thicknesses of titanium dioxide 12 which were coated onthe surface of mica 10 was about 40 nm to 90 nm, about 40 nm to 90 nm,about 90 nm to 110 nm, about 110 nm to 120 nm, about 120 nm to 135 nm,and about 135 nm to 150 nm, respectively, when the interference color ofa reflected interference light 23 was observed.

Accordingly, the transmitted light 24 which is in a complementaryrelation with the interference colors of the reflected interferencelight 23 were obtained as the interference colors of the color incliningtoward pale blue (the color in a complementary relation with gold), thecolor inclining toward blue (the color in a complementary relation withgold), green, pale yellow, yellow, and red, in the cases where the layerthicknesses of titanium dioxide were about 40 nm to 90 nm, about 40 nmto 90 nm, about 90 nm to 110 nm, about 110 nm to 120 nm, about 120 nm to135 nm, about 135 nm to 150 nm, respectively.

It is preferable that weight ratio of total titanium oxide/mica is 35/65or more in order that geometric layer thickness of titanium dioxide inmica 10 which is used in general, can be determined as 40 nm or more, asstated above.

In the following, the embodiment of the present invention is explainedaccording to the drawing.

FIG. 5 shows a general constitution of a semitransmissive liquid crystaldisplay element in accordance with an embodiment of the presentinvention.

The semitransmissive liquid crystal display 32 shown in FIG. 5 comprisesa case 34, a bezel 36 which is a frame of LCD panel, an internal lightsource 38, a reflective film 40, a semitransmissive diffusing film 42, apolarizing film 44 and 46, a glass substrate 48 and 50, a transparentelectrode 52 and 54, an alignment film 56 and 58, and a liquid crystallayer 60.

The internal light source 38 irradiates a light flux in the case wherethe internal light source is switched ON and an irradiation of the lightflux stops in the case where the internal light source is switched OFF.As for the internal light source 38, cold-cathode fluorescent lamp,hot-cathode fluorescent lamp, EL (electroluminescence), LED (lightemitting diode), incandescence lamp, and the like can be used.

A semitransmissive diffusing film 42 transmits the light flux, which wasdiffused uniformly, from said internal light source 38 to the directionof the polarizing film 44 in the case where said internal light source38 is switched ON. Also, in the case where said internal light source 38is switched OFF, an external light which is entered to thesemitransmissive diffusing film and which is diffused and reflecteduniformly, reflects to the direction of the polarizing film 44.

The polarizing film 44 is fixed on the bottom of the glass substrate 48in the drawing and the polarizing film 46 is fixed on the top of theglass substrate 50 in the drawing by adhesive, and the like. Both allowthe light flux from the semitransmissive diffusing film 42 to the lightflux of the prescribed vibration direction.

The transparent electrode 52 and 54 are composed of ITO film which ismainly composed of indium oxide and are patterned according to itsobject.

The transparent electrode 52 is installed in the top of the glasssubstrate 48 in the drawing and the transparent electrode 54 isinstalled in the bottom of the glass substrate 50 in the drawing,respectively. Orientation of the liquid crystal layer 60 (liquid crystalmolecule) between the alignment films 56 and 58 is changed by applying avoltage from the electric source 62 to the transparent electrodes 52 and54.

As for the liquid crystal layer 60, for example, nematic liquid crystalwhich is located about 6 μm layer thickness can be used. Also, tomaintain a space of the liquid crystal layer in regularly, bead-like orfiber-like fine particles (illustration is not shown) composed ofsilicon dioxide are used as a spacing material.

The semitransmissive liquid crystal display element 32 in accordancewith an embodiment of the present invention is outlined as describedabove and its function will be explained in the following.

First, on the assumption that the case where the internal light source38 is switched ON, the case that a light flux from the internal lightsource 38 is passed through the semitransmissive diffusing film, isexplained.

Some light flux from the light source 38 irradiates straightly to thesemitransmissive diffusing film 42 which is installed in its forward.Also, among the light flux from the internal light source, the otherlight flux irradiates to the semitransmissive diffusing film 42 byentered and reflected at the reflective film 40 which is installed inthe bottom portion of the drawing.

The light flux from the internal light source 38 which transmitted thesemitransmissive diffusing film 34 irradiated to the polarizing film 44.

Next, on the assumption that the case where the internal light source 38is switched OFF, the case that an external light which irradiates to thesemitransmissive diffusing film 42 is reflected, is explained.

The external light irradiated to the semitransmissive diffusing film 42through various components of the semitransmissive liquid crystaldisplay element 32, i.e., through in order of the polarizing film 46,the glass substrate 50, the transparent electrode 54, the alignment film58, the liquid crystal layer 60, the alignment film 56, the transparentelectrode 52, the glass substrate 48 and the polarizing film 44.

The external light which was irradiated and reflected at thesemitransmissive diffusing film 42 irradiated to the polarizing film 44.

The light flux which was passed through the polarizing film 44 becomes alinear polarizing light which has the prescribed vibration direction. Asshown in FIG. 6(A), the liquid crystal layer 60 (liquid crystalmolecule) is gradually twisted by the notched channel of the alignmentfilms 56 and 58 in the case where voltage is not applied. In here,non-display portion of the semitransmissive liquid crystal displayelement 32 was observed as white for the user in the case where theinternal light source 38 was switched ON, and the portion was observedas white in the case where the internal light source 38 was switchedOFF, since the light flux passes through the polarizing film 46 withchanging its direction along with a twist of the liquid crystalmolecular 60.

On the other hand, the liquid crystal layer 60 (liquid crystal molecule)is oriented to the major axis direction as shown in FIG. 4(B) in thecase where a voltage is applied to the transparent electrocodes 52 and54 which were installed in the forward and backward of the alignmentfilms 56 and 58, respectively, by the electric source 62. In this case,the light flux was shielded by the polarizing film 46 and the shieldedportion of the light flux appeared black for the user, since thevibration direction of the light flux passed through the liquid crystallayer 60 was not changed.

In here, the semitransmissive diffusing film 42 comprises the titaniumdioxide coated mica 14 shown in FIG. 3. In the titanium dioxide coatedmica 14, the layer thickness and the percentage of the titanium dioxidewhich was coated on the surface of mica were considered so as that thetransmitted light 24 and the reflected light 23 of the semitransmissivediffusing film 42 can be obtained with the interference color of thedesired color tone.

Therefore, the interference colors of the titanium dioxide coated mica14 were favorably blended and the transmitted light 24 and the reflectedlight 23 of the semitransmissive diffusing film 42 was obtained with thereflected light 23 interference color of the desired color tone as awhole.

Also, the semitransmissive diffusing film of the present invention hadhigh using efficiency of the light in comparison with the diffusing filmwhich obtained its color tone by absorbing the optical component of thespecific wavelength to color pigment or pigment as is conventional.Accordingly, vivid color tone can be obtained.

In FIG. 4, a transmissive liquid crystal display element can beconstructed by using a transmissive diffusing film instead of asemitransmissive diffusing film. The diffusing film is used instead of areflecting film and a reflective liquid crystal display element can beconstructed by using a reflective diffusing film when the back lighting38 and the reflective film 40 are not used.

Also, as for the powder which has a characteristic interference color ofthe present invention, the more beautiful color tone can be obtained byusing titanium dioxide coated synthetic mica which is coated titaniumdioxide on the surface of synthetic mica, because the powders used insynthetic mica have less impurities in comparison with the powders usedin natural mica.

Manufacturing examples of synthetic mica are shown in the followingmanufacturing examples 1 to 3.

MANUFACTURING EXAMPLE 1

After mixing 40 parts of silicic anhydride, 30 parts of magnesium oxide,13 parts of aluminum oxide and 17 parts of potassium silicofluoride, themixture was dissolved at 1500° C. 100 parts of synthetic fluorinephlogopite powder (synthetic mica 1) diameter 2.5 μm (circularconversion value measured by CEDIGRAPH 5000-01 manufactured byMicromelitec Inc.: the followings are the same with this) was obtainedby grinding roughly and finely synthetic fluorine phlogopite which wascrystallized at 1350° C.

MANUFACTURING EXAMPLE 2

After mixing 40 parts of silicic anhydride, 30 parts of magnesium oxide,13 parts of aluminum oxide and 17 parts of potassium silicofluoride, themixture was dissolved at 1500° C. 100 parts of synthetic fluorinephlogopite powder (synthetic mica 2) diameter 2.0 μm was obtained bygrinding roughly and finely synthetic fluorine phlogopite which wascrystallized at 1350° C.

MANUFACTURING EXAMPLE 3

After mixing 40 parts of silicic anhydride, 30 parts of magnesium oxide,13 parts of aluminum oxide and 17 parts of potassium silicofluoride, themixture was dissolved at 1500° C. 100 parts of synthetic fluorinephlogopite powder (synthetic mica 3) diameter 8.5 μm was obtained bygrinding roughly and finely synthetic fluorine phlogopite which wascrystallized at 1350° C.

Next, the methods for coating titanium dioxide on the surface ofsynthetic mica shown in the above-mentioned manufacturing examples 1 to3 are shown in the following manufacturing examples 4 to 7.

MANUFACTURING EXAMPLE 4

50 parts by weight of said synthetic mica was added to 500 parts ofion-exchanged water and the mixture was stirred sufficiently anddispersed uniformly. 208.5 parts of 40% titanyl sulfate water solutionwas added to the dispersion and the mixture was stirred and boiled for 6hours. After cooling, the mixture was filtered and washed with water. 90parts of titanium dioxide coated synthetic mica (titanated mica 1) wascalcining the mixture at 90° C.

MANUFACTURING EXAMPLE 5

50 parts by weight of said synthetic mica was added to 500 parts ofion-exchanged water and the mixture was stirred sufficiently anddispersed uniformly. 312.5 parts of 40% titanyl sulfate water solutionwas added to the dispersion and the mixture and boiled for 6 hours.After cooling, the mixture was filtered and washed with water 100 partsof titanium dioxide coated synthetic mica (titanated mica 2) wascalcining the mixture at 90° C.

MANUFACTURING EXAMPLE 6

50 parts by weight of said synthetic mica was added to 500 parts ofion-exchanged water and the mixture was stirred sufficiently anddispersed uniformly. 208.5 parts of 40% titanyl sulfate water solutionwas added to the dispersion and the mixture and boiled for 6 hours.After cooling, the mixture was filtered and washed with water. 90 partsof titanium dioxide coated synthetic mica (titanated mica 3) wasobtained by drying the mixture at 100° C.

MANUFACTURING EXAMPLE 7

50 parts by weight of said synthetic mica was added to 500 parts ofion-exchanged water and the mixture was stirred sufficiently anddispersed uniformly. 312.5 parts of 40% titanyl sulfate water solutionwas added to the dispersion and the mixture was stirred and boiled for 6hours. After cooling, the mixture was filtered and washed with water.100 parts of titanium dioxide coated synthetic mica (titanated mica 4)was obtained by calcining the mixture at 90° C.

Transmissive Diffusing Film

As for a transmissive diffusing film, a transmissive diffusing film thata polymer which was formed by dispersing the powder in accordance withthe present embodiment with film state (e.g., layer thickness 10 μm to500 μm) can be directly used. Also, a transmissive diffusing film whichwas formed in film state as like this can be used with set on atransparent substrate. Further, a transmissive diffusing film that thepowder in accordance with the present embodiment was incorporated in asubstrate can be used.

As for the substrate, glass, nitrocellulose, acrylic polymer,polycarbonate, polyester, polyurethane, polyethylene terephthalate (PET)and the like can be used.

Also, a diffusing film can be manufactured by coating the powder inaccordance with the present invention on the substrate as an ink.

As for the ink prepared with said powder, the ink which was dispersedand mixed said powder into a resin binder such as polyacryl,polyurethane, polycarbonate, polyester and the like, can be used.

Also, as for said coating methods, screen printing method, roll coater,offset printing method, knife coater, comma coater, and the like can belisted as an example.

Also, as for the substrate, transparent, semitransparent and whiteplastic sheet (thickness about 10 μm to 1000 μm), and the like can beused. For example, polyolefines such as polyvinyl chloride,polyethylene, polypropylene, and the like, polyesters such aspolyethylene terephthalate and the like, resins such as polystyrene,polycarbonate, acrylic resin, polyurethane resin and the like, can beused. Also, 20 wt % to 100 wt % of a plasticizer can be added to theresin as occasion demands.

Also, surface finishing such as embossing finish and the like can beconducted, as occasion demands.

Further, 1 wt % to 50 wt % of white pigment, transparent particle,plastic bead, and the like can be added with respect to the powder ofthe present embodiment for the purpose of toning the color tone of thetransmitted light at the diffusing film.

As for the white pigment, titanium dioxide coated natural or syntheticmica which has no interference color, natural mica, synthetic mica,barium sulfate, barium oxide, titanium dioxide, zinc oxide, magnesiumoxide, titanium dioxide, silica particle, plastic bead, acrylic bead,nylon bead, polystyrene bead, polysilicone bead and the like can belisted as an example.

As stated above, according to the liquid crystal display element 26 inaccordance with the present embodiment, titanium dioxide coated mica 14which was shown in FIG. 3 was used in the diffusing film 38 as thepowder.

Therefore, a transmitted light at the diffusing film 38 can be obtainedwith white color in the case where white light was irradiated to thediffusing film 38, because an optical component which has specificwavelength absorbed by titanium dioxide coated mica 14, can be favorablydiffused as an incident light to the diffusing film 38 and can befavorably complemented by the interference color of titanium dioxidecoated mica 14.

However, a diffusing film, a lighting unit, and a liquid crystal displayelement of the present invention are not limited to said variousconstitutions, the various formations can be adopted within the range ofthe essentials of the invention.

Namely, the diffusing film of the present embodiment can be used for TNtype liquid crystal display element, STN type display, DSTN typedisplay, F-STN type display, CSH type display, ferroelectric liquidcrystal type display element, and the like.

In said constitutions, the case that one of titanium dioxide coated mica14 shown in FIG. 2 was used as the powder, was explained. Instead ofthis, two or more titanium dioxide coated mica (powder) whoseinterference colors are complementary to each other, can be used.

Also, concrete manufacturing process of the liquid crystal displayelement of the present embodiment is shown in the followingmanufacturing process 1-1.

Manufacturing Process 1-1

First, the powder in accordance with the present invention was added toan acrylic resin lacquer. Then, the mixture which was dispersed andmixed by a homogenizer was printed on polyethylene terephthalate whichdeposited aluminum so as that thickness could be 50 μm by screenprinting method. A diffusing film was manufactured by heating andhardening it at 60° C.

A transmissive liquid crystal display element was manufactured bysticking the obtained diffusing film in the state that said powder layerwas set to the top, to the reverse side of normally white mode TN-typeliquid crystal display (installed so as to cross the polarizing filmeach other).

FIG. 7 shows the principal part of a liquid crystal display element inaccordance with one embodiment of the present invention. The portionswhich are equivalent to FIG. 3 are shown by adding a mark 100 and arenot explained.

The characteristic point of this embodiment was that two kinds of thepowder that each interference color was in a complementary relation,were used.

In FIG. 7, in the case where a layer thickness of a titanium dioxide112a in a titanium dioxide coated mica 114a was determined so as that atransmitted light 124a could be obtained by, for example, redinterference color, a layer thickness of a titanium dioxide 112b in atitanium dioxide coated mica 114b was determined so as that atransmitted light 124b can be obtained with green interference colorwhich was in a complementary relation with red interference color ofsaid titanium dioxide coated mica 114a.

Therefore, in the case where white light was irradiated to the diffusingfilm 138 of the present embodiment, the transmitted light 124a (e.g.,red interference color) of the titanium dioxide coated mica 114a and thetransmitted light 124b (e.g., green interference color) of the titaniumdioxide coated mica 114b were favorably blended. Accordingly, atransmitted light at the diffusing film could be obtained with whiteinterference color as a whole.

In the following, a preferable examples of the present invention will beexplained. However, the present invention is not limited to theseexamples.

EXAMPLE 1-1

In example 1-1, a substance which dispersed titanium dioxide coated micaA (average particle diameter 10 μm to 60 μm, total 1.0 g) in 15 g ofacrylic lacquer, was coated on PET film by a barcoater with 200 μm layerthickness with dry state.

In this example 1-1, the layer thickness distribution of titaniumdioxide was determined so as that titanium dioxide coated mica A had aninterference color of the same wave range with an absorption wave range.Namely, the layer thickness of titanium dioxide was determined as 20 to90 nm in titanium dioxide coated mica A.

In FIG. 8, a comparison result of light transmittance between the casesthat the diffusing film of example 1-1 and conventional diffusing filmwere used is shown.

b in FIG. 8 is a diffusing film in accordance with example 1-1 and c inFIG. 8 is the diffusing film which used titanium dioxide coated micathat layer thickness of titanium dioxide which was coated on the surfaceof mica was not determined at all.

As a result, it is understood that light transmittance was almost flatin the range of 400 nm to 700 nm in the case where b in FIG. 8 whichshows this example 1-1 was compared with c in FIG. 8 which showsconventional example.

Namely, according to the diffusing film of this example 1-1, it isunderstood that the optical component which had the absorption waverange of titanium dioxide coated mica A was favorably complemented bythe interference color of titanium dioxide coated mica A.

EXAMPLE 1-2

In example 1-2, a substance which dispersed titanium dioxide coated micaB and C (both average particle diameters 10 μm to 60 μm, total 2.0 g) in15 g of acrylic lacquer, was coated on PET film by a barcoater with 200μm layer thickness with dry state.

In this example 1-2, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica B was obtained with yellow interference color. Namely, the layerthickness of titanium dioxide was determined as 40 nm to 60 nm intitanium dioxide coated mica B.

To the contrary, in titanium dioxide coated mica C, the layer thicknessof titanium dioxide was determined so as that the transmitted light oftitanium dioxide coated mica C was obtained with blue interference colorwhich was in a complementary relation with yellow interference color ofsaid titanium dioxide coated mica B. Namely, the layer thickness oftitanium dioxide was determined as 60 nm to 80 nm in titanium dioxidecoated mica C.

In FIG. 9, a comparison result of light transmittance in the cases wherethe percentages of titanium dioxide coated mica B and C which were usedin the diffusing film of this example 1-2 were variously changed isshown.

Each of d, e, f, g and h in FIG. 9 shows the light transmittance in thecases where the percentages of titanium dioxide coated mica B and C were100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the transmitted light in thediffusing film could be obtained with yellow interference color bytitanium dioxide coated mica B, as shown in d of FIG. 9 in the casewhere the percentage of titanium dioxide coated mica B and C was 100:0.

Also, it is understood that the transmitted light in the diffusing filmcould be obtained with blue interference color by titanium dioxidecoated mica C, as shown in h of FIG. 9 in the case where the percentageof titanium dioxide coated mica B and C was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica B and C was 50:50, it is understood that the transmittedlight in the diffusing film could be obtained with white interferencecolor that was favorably blended by yellow interference color oftitanium dioxide coated mica B and blue interference color of titaniumdioxide coated mica C as shown in f of FIG. 9.

According to the diffusing film of this example 1-2, the transmittedlight in the diffusing film could be obtained with much whiterinterference color by using titanium dioxide coated mica B and C at thepercentage of 50:50. Namely, in the case where white light was enteredinto the diffusing film, yellow interference color of titanium dioxidecoated mica B and blue interference color of titanium dioxide coatedmica C were favorably blended.

Further, though the transmitted light in the diffusing film could beobtained with much whiter interference color in the case where titaniumdioxide coated mica B and C were used at the percentage of 50:50 asstated above, the transmitted light in the diffusing film still could beobtained with satisfactory and nearly white color tone in the caseswhere titanium dioxide coated mica B and C were used at the percentagesof 25:75 to 75:25 as shown in e and g of FIG. 9.

EXAMPLE 1-3

In example 1-3, a substance which dispersed titanium dioxide coated micaD and titanium dioxide (TiO₂) as white pigment E (both average particlediameters 10 μm to 60 μm, total 2.0 g) in 15 g of acrylic lacquer, wascoated on PET film by a barcoater with 200 μm layer thickness with drystate.

In this example 1-3, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica C was obtained with yellow interference color. Namely, the layerthickness of titanium dioxide was determined as 60 nm to 80 nm intitanium dioxide coated mica D.

In FIG. 10, a comparison result of light transmittance in the case wherethe percentages of titanium dioxide coated mica D and white pigment Ewhich were used in the diffusing film of this example 1-3 were variouslychanged is shown.

Each of i, j, k and I in FIG. 10 shows the light transmittance in thecases where the percentages of titanium dioxide coated mica D and whitepigment E were 75:25, 50:50, 25:75, 0:100, respectively.

As a result, as is clear from i to l in FIG. 9, according to thediffusing film of this example 1-3, it is understood that the color toneof the transmitted light in the diffusing film could be toned properlyby adding white pigment E with respect to titanium dioxide coated micaD.

EXAMPLE 1-4

In example 1-4, a substance which dispersed titanium dioxide coated micaF and G (both average particle diameters 10 μm to 60 μm, total 2.0 g) in15 g of acrylic lacquer, was coated on PET film by a barcoater with 200μm layer thickness with dry state.

In this example 1-4, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica F was obtained with green interference color. Namely, the layerthickness of titanium dioxide was determined as 80 nm to 100 nm intitanium dioxide coated mica F.

To the contrary, the layer thickness of titanium dioxide was determinedso as that the transmitted light of titanium dioxide coated mica G wasobtained with red interference color which was in a complementaryrelation with green interference color of said titanium dioxide coatedmica F. Namely, the layer thickness of titanium dioxide was determinedas 140 nm to 160 nm in titanium dioxide coated mica G.

In FIG. 11, a comparison result of light transmittance in the case wherethe percentages of titanium dioxide coated mica F and G which were usedin the diffusing film of this example 1-4 were variously changed isshown.

Each of m, n, o, p, and q in FIG. 11 shows the light transmittance inthe cases where the percentages of titanium dioxide coated mica F and Gwere 100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the transmitted light in thediffusing film could be obtained with green interference color bytitanium dioxide coated mica F, as shown in m of FIG. 11 in the casewhere the percentage of titanium dioxide coated mica F and G was 100:0.

Also, it is understood that the transmitted light in the diffusing filmcould be obtained with red interference color by titanium dioxide coatedmica G, as shown in q of FIG. 11 in the case where the percentage oftitanium dioxide coated mica F and G was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica F and G was 50:50, it is understood that the transmittedlight in the diffusing film could be obtained with white interferencecolor which was favorably blended by green interference color oftitanium dioxide coated mica F and red interference color of titaniumdioxide coated mica G as shown in o of FIG. 11.

According to the diffusing film of this example 1-4, the transmittedlight in the diffusing film could be obtained with much whiterinterference color by using titanium dioxide coated mica F and G at thepercentage of 50:50. Namely, in the case where white light was enteredinto the diffusing film, green interference color of titanium dioxidecoated mica F and red interference color of titanium dioxide coated micaG were favorably blended.

Further, though the transmitted light in the diffusing film could beobtained much whiter interference color in the case where titaniumdioxide coated mica F and G were used at the percentage of 50:50 asstated above, the transmitted light in the diffusing film could beobtained with satisfactory and nearly white color tone in the case wheretitanium dioxide coated mica F and G were used at the percentages of25:75 to 75:25 as shown in n and p of FIG. 11.

As explained above, according to the diffusing film of the presentinvention, the powder which has an interference color of the same waverange with an absorption wave range was used. Therefore, the transmittedlight in the diffusing film could be obtained with white, in the casewhere white light was entered into the diffusing film, since an opticalcomponent which was absorbed by the powder was favorably complemented bythe interference color of the powder.

Also, according to the reflective diffusing film of the presentinvention, instead of said powder, two or more of the powders which werecomplementary to each other were used. Therefore, the transmitted lightin the diffusing film could be obtained with white, since theinterference color of these powder could be favorably blended.

In said reflective diffusing film, the powder that the interferencecolor was in a complementary relation could be obtained the transmittedlight in the diffusing film with satisfactory white interference colorin the case where 25% to 75% of one powder was added to the otherpowder.

Also, the more beautiful color tone can be obtained in the case wheretitanium dioxide coated synthetic mica is used on the surface ofsynthetic mica as said powder, because the powders used synthetic micahas much less impurities in comparison with the powders used naturalmica.

According to the liquid crystal display element in accordance with thepresent invention, a beautiful image can be obtained by using suchdiffusing film for the lighting unit and the liquid crystal displayelement, since a light from a light source can be efficiently used.

Semitransmissive Diffusing Film

According to the semitransmissive diffusing film of the presentinvention, the semitransmissive diffusing film comprises the powderwhich has the interference color as stated above. Also, the transmittedlight or the reflected light in the semitransmissive diffusing film wasobtained with the interference color of the desired color tone as awhole by changing properly the kinds and percentages of these powdersand by blending the interference colors of these powders.

Therefore, the semitransmissive diffusing film of the present inventionhas high using efficiency of the light in comparison with the diffusingfilm which was obtained its color tone by absorbing an optical componentof the specific wavelength into color pigment or pigment as inconventional. Accordingly, a stable vivid color tone can be obtained.

Also, the transmitted light or the reflected light of thesemitransmissive diffusing film can be obtained with the interferencecolor of the desired color tone by changing properly the kinds and thepercentages of these powders. Further, the favorable toning of the colortone is facilitated.

In said semitransmissive diffusing film, when the powder that theinterference color is in a complementary relation, the transmitted lightand the reflected light in the semitransmissive diffusing film withsatisfactory white interference color can be obtained in the case where25% to 75% of one powder is added to the other powder.

Also, in said semitransmissive diffusing film, in the case where saidpowder is set on the substrate, it is preferable that an amount of saidpowder on the substrate is 0.01 g/m² to 100 g/m². To the contrary, inthe case where said powder is set in the substrate, it is preferablethat an amount of said powder is 1 wt % to 70 wt % in the substrate.Namely, it is possible to favorably coexist light reflectance and lighttransmittance of the semitransmissive diffusing film by theselimitations.

Also, in the semitransmissive liquid crystal display element inaccordance with the present invention, the powder which generates acolored interference light was used directly. The transmittedinterference light was obtained in the case where the internal lightsource was switched ON and the reflected interference light which wascomplementary to said transmitted interference light was obtained in thecase where the internal light source was switched OFF. Thus, anexcellent design can be revealed by obtaining the various color tones.Also, these color tones can be obtained certainly and stably.

Also, it is preferable that the semitransmissive diffusing film inaccordance with the present invention which can obtain the transmittedlight and the reflected light with white interference color, is used forthe semitransmissive liquid crystal display element of black-and-whitedisplay. Namely, it is possible to obtain brightness, visibility, highcontrast and wide viewing angle by using said semitransmissive diffusingfilm.

It is also preferable that the semitransmissive diffusing film inaccordance with the present invention which can obtain the transmittedlight and the reflected light with the colored interference color of thedesired color is used for the semitransmissive liquid crystal displayelement of two-color display. Namely it is possible to obtain design,brightness, visibility, high contrast and wide viewing angle by usingsaid semitransmissive diffusing film without using such as a colorfilter.

Further, it is also preferable that the semitransmissive diffusing filmin accordance with the present invention which can obtain thetransmitted light and the reflected light with white interference coloris used for the semitransmissive liquid crystal display element of colordisplay. Namely, it is possible to obtain high reproducibility of colorin the color filter, brightness, visibility, high contrast, and wideviewing angle, by using the semitransmissive diffusing film, because,for example, an incident light from said semitransmissive diffusing filmto the color filter can be obtained with much whiter color tone.

The powder which has characteristic interference color in the presentinvention, is typified as shown in FIG. 12.

First, the case where an internal light source of a semitransmissiveliquid crystal display element was switched on, is the same as in thecase of FIG. 7, since a light flux 16 from the internal light source wastransmitted at a semitransmissive diffusing film 42. Namely, forexample, in the case where white transmitted light is obtained as awhole by entering the light flux 116 (white light) from the internallight source to the semitransmissive diffusing film 42 (FIG. 12) of thisembodiment, when the layer thickness of titanium dioxide 12a in onetitanium dioxide coated mica 14a can be obtained the transmitted light24a with red interference right, the layer thickness of titanium dioxide12b in other titanium dioxide coated mica 14b is determined as the layerthickness which can be obtained by green interference color which is ina complementary relation with red. Accordingly, in the case where thelight flux 16 from the internal light source is entered to thesemitransmissive diffusing film 42 of this embodiment, the transmittedlight of the semitransmissive diffusing film 42 can be obtained withmuch whiter interference color as a whole, because the transmitted light24a (e.g., red interference color) of titanium dioxide coated mica 14aand the transmitted light 24b (e.g., green interference color) oftitanium dioxide coated mica 14b are favorably blended.

Next, on the assumption that the case where the internal light source isswitched OFF, the case that an external light 26 which is entered andreflected at the semitransmissive diffusing film 42 is explained.

First, as shown in FIG. 12, in the case where the internal light sourcewas switched OFF, a large part of the external light 26 became areflected light 28 and 30, since the light flux entered into thesemitransmissive diffusing film 42 was only the external light 26 inpractical.

In here, when white external light 26 was entered into thesemitransmissive diffusing film 42 in accordance with this embodiment,the reflected light at semitransmissive diffusing film 42 was obtainedwith interference color of the color tone which is in a complementaryrelation with the color tone of the transmitted light atsemitransmissive diffusing film 42 shown in FIG. 7 as a whole, becausethe interference colors of the reflected light at titanium dioxidecoated mica 14a and titanium dioxide coated mica 14b were favorablyblended.

Also, an improvement of the design can be planned, since a differencecolor tone can be obtained according to the cases that the internallight source is switched ON and OFF, by using one of titanium dioxidecoated mica 14 which has the interference color in the substrate 18, asstated above.

Also, the semitransmissive diffusing film in accordance with oneembodiment of the present invention can be manufactured by setting thesepowders on the substrate (nitrocellulose, acrylic polymer,polycarbonate, polyester, polyurethane, polyethylene terephthalate (PET)and the like), for example, in the conditions that 10 nm to 1000 nm ofthe layer thickness and 0.01 g/m² to 100 g/m² per unit area.

The semitransmissive diffusing film in accordance with one embodiment ofthe present invention can be also manufactured by incorporating 1 wt %to 70 wt % of these powders into the substrate.

The more concrete manufacturing processes of such semitransmissivediffusing films were shown in the following manufacturing processes 1 to2.

Manufacturing Process 2-1

A semitransmissive diffusing film can be manufactured by printing orcoating the powder (two or more of the powders which has theinterference color) on the substrate as an ink.

As for the ink prepared with said powder, the ink which were dispersedand mixed said powder into a resin binder such as polyacryl,polyurethane, polycarbonate, polyester and the like can be used.

Also, as for said coating methods, screen printing method, roll coater,offset printing method, knife coater, comma coater, and the like can belisted as an example.

Also, as for the substrate, transparent, semitransparent and whiteplastic sheet (thickness about 10 μm to 1000 μm), and the like can beused. For example, polyolefines such as polyvinyl chloride,polyethylene, polypropylene, and the like, polyesters such aspolyethylene terephthalate and the like, resins such as polystyrene,polycarbonate, acrylic resin, polyurethane resin and the like can beused. Also, 20 wt % to 100 wt % of a plasticizer can be added to theresin as occasion demands.

Also, surface finishing such as embossing finish and the like can beconducted, as occasion demands.

Manufacturing Process 2-2

A semitransmissive diffusing film can be manufactured by incorporatingthe powder (two or more of the powders which has the interference color)into a plastic.

As for said plastic, transparent, semitransparent and white plasticsheet (thickness about 10 μm to 1000 μm), and the like can be used. Forexample, polyolefines such as polyvinyl chloride, polyethylene,polypropylene, and the like, polyesters such as polyethyleneterephthalate and the like, resins such as polystyrene, polycarbonate,acrylic resin, polyurethane resin and the like can be used. Also, 20 wt% to 100 wt % of a plasticizer can be added to the resin as occasiondemands.

Further, 1 wt % to 50 wt % of white pigment, transparent particle,plastic bead, and the like can be added with respect to these powdersfor the purpose of toning the color tone of the transmitted light at thesemitransmissive diffusing film.

As for the white pigment, titanium dioxide coated mica which has notinterference color, mica, barium sulfate, barium oxide, titaniumdioxide, zinc oxide, magnesium oxide, titanium dioxide, transparentparticle, silica particle, plastic bead, acryl, nylon, polystyrene,polysilicone and the like can be listed as an example. Also, it ispreferable that a particle diameters of these powders are 0.1 μm to 200μm.

Also, the more beautiful color tone can be obtained in the case wheretitanium dioxide coated synthetic mica which was coated titanium dioxideon the surface of synthetic mica as the powder which has characteristiccolor tone in the present invention, because the powders used syntheticmica has much less impurities in comparison with the powders usednatural mica.

Further, the transmitted light or the reflected light of thesemitransmissive diffusing film 42 can be obtained the interferencecolor which has the desired color tone, by properly changing the layerthicknesses and the percentages of titanium dioxides of titanium dioxidecoated mica 14a and 14b. Also, favorable toning of the color tone isfacilitated.

Also, the color tones of the transmitted light and the reflected lightat the semitransmissive diffusing film 42 were complementary to eachother. Accordingly, for example, in the semitransmissive liquid crystaldisplay element 32 that one powder which had a colored interferencelight, a different color tones as shown in the following TABLE 1 wereobtained according to the internal light source 38 was switched ON andOFF.

                  TABLE 1                                                         ______________________________________                                        Internal light source ON                                                                        Internal light source OFF                                   ______________________________________                                        Blue              Yellow                                                      Yellow            Blue                                                        Red               Green                                                       Green             Red                                                         ______________________________________                                    

In sum, for example, in the case where non-display portion of thesemitransmissive liquid crystal display element was observed as blue forthe user when the internal light source 38 was switched ON, the portionwas observed as yellow which was complementary to blue when the internallight source 38 was switched OFF.

Thus an excellent design of the semitransmissive liquid crystal displayelement 32 can be revealed by properly adjusting the layer thicknessesand the percentages of titanium dioxide of titanium dioxide coated mica14 in the substrate 18 of the semitransmissive diffusing film 42, so asthat the color tone of the semitransmissive liquid crystal displayelement 32 becomes different according to the cases where the internallight source is switched ON and OFF.

As stated above, according to the semitransmissive liquid crystaldisplay element 32 in accordance with this embodiment, thesemitransmissive diffusing film 42 comprises titanium dioxide coatedmica 14a and 14b which has an interference color. Namely, thetransmitted light or the reflected light at the semitransmissivediffusing film 42 was obtained by the interference color of the desiredcolor tone as a whole by properly changing the layer thicknesses and thepercentages of titanium dioxide of titanium dioxide coated mica 14a and14b and by blending the interference colors of these titanium dioxidecoated mica 14a and 14b.

Therefore, the semitransmissive diffusing film of the present inventionhad high using efficiency of the light in comparison with the diffusingfilm which was obtained its color tone by absorbing the opticalcomponent of the specific wavelength to color pigment or pigment as inconventional. Accordingly, vivid color tone can be obtained in stable.

Also, the transmitted light or the reflected light at thesemitransmissive diffusing film 42 can be obtained by the interferencecolor of the desired color tone by properly changing the layerthicknesses and the percentages of titanium dioxide of titanium dioxidecoated mica 14a and 14b. Also, favorable toning of the color tone isfacilitated.

Also, brightness, visibility, high contrast and wide viewing angle canbe obtained by using the semitransmissive diffusing film in accordancewith one embodiment which was considered the kinds and percentages ofthese powders so as that the transmitted light or the reflected lightcan be obtained with white interference color, in the semitransmissiveliquid crystal display element of black-and-white display.

Further, high reproducibility of color in the color filter, brightness,visibility, high contrast, and wide viewing angle can be obtained byusing the semitransmissive diffusing film in accordance with oneembodiment which was considered the kinds and percentages of thesepowders so as that the transmitted light or the reflected light can beobtained with white interference color, in the semitransmissive liquidcrystal display element of color display. Because, for example, anincident light from said semitransmissive diffusing film to the colorfilter was obtained with much whiter color tone by using thesemitransmissive diffusing film.

Also, an excellent design can be revealed in the case where thesemitransmissive liquid crystal display element 32 in accordance withthis embodiment was determined so as to obtain the difference colortones according to the cases that the internal light source 38 wasswitched ON and OFF. Also, these color tones can be obtained certainlyand stably.

Also, design, brightness, visibility, high contrast, and wide viewingangle can be obtained by using the semitransmissive diffusing film inaccordance with one embodiment which was considered the sorts and thepercentages of these powders so as that the transmitted light or thereflected light can be obtained with white interference color, in thesemitransmissive liquid crystal display element of two-color display,because the more beautiful desired color tone can be obtained withoutusing such as a color filter.

Also, the more beautiful color tone can be obtained in the case wheretitanium dioxide coated synthetic mica which was coated titanium dioxideon the surface of synthetic mica shown in said manufacturing examples 1to 7 was used as these titanium dioxide coated mica 14a and 14b, becausethe powders used synthetic mica has much less impurities in comparisonwith the powders used natural mica.

In the following, the preferable examples of the present invention willbe explained. However, the present invention is not limited to theseexamples.

EXAMPLE 2-1

In example 2-1, a substance which dispersed titanium dioxide coated micaA and B whose interference colors are complementary to each other(average particle diameter 10 μm to 60 μm, total 2.0 g) in 15 g ofacrylic lacquer with 50:50, was coated on PET film by a barcoater with200 μm layer thickness with dry state.

In this example 2-1, the layer thickness of titanium dioxide which wascoated on the surface of mica was determined as about 40 nm to 60 nm inthe titanium dioxide coated mica A and the layer thickness of titaniumdioxide which was coated on the surface of mica was determined as about60 nm to 80 nm in the titanium dioxide coated mica B.

In FIG. 13, a comparison result of light transmissive spectrum betweenthe cases that the semitransmissive diffusing film of example 2-1 andthe conventional semitransmissive diffusing film were used is shown.These light transmittances are the light transmittance at the time (whenthe reflected light from the semitransmissive diffusing film) wasvertically received in the condition of diffused lighting of whitelight.

b in FIG. 13 is the semitransmissive diffusing film in accordance withexample 2-1 and c in FIG. 13 is the semitransmissive diffusing film thatone titanium dioxide coated mica which was never considered the layerthickness of titanium dioxide which was coated on the surface of mica.

As a result, it is understood that light transmittance was almost flatin the wave range of 400 nm to 700 nm in the case where b in FIG. 13which shows example 2-1 was compared with c in FIG. 13 which shows theconventional example.

In FIG. 14, a comparison result of light reflective spectrum between thecases that the semitransmissive diffusing film of example 2-1 and theconventional semitransmissive diffusing film or the reflective film wereused is shown. These light reflectances are the light reflectance at thetime (when the reflected light from the semitransmissive diffusing film)was vertically received in the condition of diffused lighting of whitelight.

d, e and f in FIG. 14 are the light reflectance of the semitransmissivediffusing film in accordance with example 2-1, the semitransmissivediffusing film which used one of general pearly pigment in conventionaland general silver deposited film (reflective film) in conventional,respectively.

As a result, it is understood that light reflectance was almost flat inthe case where d in FIG. 14 which shows example 2-1 was compared with eand f in FIG. 14 which shows the conventional examples. In particular,it is understood that light reflectance was largely improved in d ofFIG. 14 which shows example 2-1.

Namely, according to the semitransmissive diffusing film of this example2-1, it is understood that the interference colors of the titaniumdioxide coated mica A and the titanium dioxide coated mica B werefavorably blended and the color tones of the transmitted light and thereflected light were obtained with much whiter than conventionaldiffusing film.

EXAMPLE 2-2

In example 2-2, a substance which was uniformly dispersed titaniumdioxide coated mica C and D whose interference colors are complementaryto each other (average particle diameter 10 μm to 60 μm, total 2.0 g) in15 g of acrylic lacquer, was coated on PET film by a barcoater with 200μm layer thickness with dry state.

In this example 2-2, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica C could be obtained with yellow interference color. Namely, thelayer thickness of titanium dioxide was determined as 40 nm to 60 nm intitanium dioxide coated mica C.

To the contrary, the layer thickness of titanium dioxide was determinedso as that the transmitted light of titanium dioxide coated mica D wasobtained with blue interference color which was complementary to yellowinterference color of said titanium dioxide coated mica C. Namely, thelayer thickness of titanium dioxide was determined as 60 nm to 80 nm intitanium dioxide coated mica D.

In FIG. 15, a comparison result of light transmittance in the caseswhere the percentages of titanium dioxide coated mica C and D which wereused in the semitransmissive diffusing film of this example 2-2 werevariously changed is shown. These light transmittances are the lighttransmittance at the time (when the reflected light from thesemitransmissive diffusing film) was vertically received in thecondition of diffused lighting of white light.

g, h, i, j and k in FIG. 15 were the light transmittance in the casewhere the percentages of titanium dioxide coated mica C and D were100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the transmitted light in thesemitransmissive diffusing film can be obtained yellow interferencecolor of titanium dioxide coated mica C as shown in g of FIG. 15 in thecase where the percentage of titanium dioxide coated mica C and D whichwere used in the semitransmissive diffusing film of this example 2-2 was100:0.

Also, it is understood that the transmitted light in thesemitransmissive diffusing film can be obtained blue interference colorof titanium dioxide coated mica D as shown in k of FIG. 15 in the casewhere the percentage of titanium dioxide coated mica C and D was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica C and D was 50:50, it is understood that the transmittedlight in the semitransmissive diffusing film could be obtained with muchwhiter interference color which was favorably blended by yellowinterference color of titanium dioxide coated mica C and blueinterference color of titanium dioxide coated mica D as shown in i ofFIG. 15.

According to the semitransmissive diffusing film of this example 2-2,the transmitted light in the semitransmissive diffusing film could beobtained with much whiter interference color by using titanium dioxidecoated mica C and D at the percentage of 50:50 in the case where whitelight was entered into the semitransmissive diffusing film, since yellowinterference color of titanium dioxide coated mica C and blueinterference color of titanium dioxide coated mica D were favorablyblended.

Further, though the transmitted light in the semitransmissive diffusingfilm could be obtained with much whiter interference color in the casewhere titanium dioxide coated mica C and D were used at the percentageof 50:50 as stated above, the transmitted light in the semitransmissivediffusing film could be obtained with satisfactory and nearly whitecolor tone in the case where titanium dioxide coated mica C and D wereused at the percentages of 25:75 to 75:25 as shown in h and j of FIG.15.

EXAMPLE 2-3

In example 2-3, a substance which dispersed titanium dioxide coated micaE and titanium dioxide (TiO₂) as white pigment E (average particlediameter 10 μm to 60 μm, total 2.0 g) in 15 g of acrylic lacquer, wascoated on PET film by a barcoater with 200 μm layer thickness with drystate.

In this example 2-3, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica E could be obtained with yellow interference color. Namely, thelayer thickness of titanium dioxide was determined as 60 nm to 80 nm intitanium dioxide coated mica E.

In FIG. 16, a comparison result of light transmittance in the caseswhere the percentages of titanium dioxide coated mica E and whitepigment F which were used in the semitransmissive diffusing film of thisexample 2-3 were variously changed is shown.

l, m, n and o in FIG. 16 were the light transmittance in the cases wherethe percentages of titanium dioxide coated mica E and white pigment Fwere 75:25, 50:50, 25:75, 0:100, respectively.

As a result, as is clear from l to o in FIG. 16, according to thesemitransmissive diffusing film of this example 2-3, it is understoodthat the color tone of the transmitted light of the semitransmissivediffusing film can be toned easily by adding white pigment F withrespect to the titanium dioxide coated mica E for the purpose of toningthe color tone of the transmitted light of the semitransmissivediffusing film.

EXAMPLE 2-4

In example 2-4, a substance which was uniformly dispersed titaniumdioxide coated mica G and H whose interference colors are complementaryto each other (average particle diameter 10 μm to 60 μm, total 2.0 g) in15 g of acrylic lacquer, was coated on PET film by a barcoater with 200μm layer thickness with dry state.

In this example 2-4, the layer thickness of titanium dioxide wasdetermined so as that the transmitted light of titanium dioxide coatedmica G could be obtained with green interference color. Namely, thelayer thickness of titanium dioxide was determined as 80 nm to 100 nm inthe titanium dioxide coated mica G.

To the contrary, the layer thickness of titanium dioxide was determinedso as that the transmitted light of titanium dioxide coated mica H canbe obtained with red interference color which was complementary to greeninterference color of said titanium dioxide coated mica G. Namely, thelayer thickness of titanium dioxide was determined as 140 nm to 160 nmin the titanium dioxide coated mica H.

In FIG. 17, a comparison result of light transmittance in the caseswhere the percentages of titanium dioxide coated mica G and H which wereused in the semitransmissive diffusing film of this example 2-4 werevariously changed is shown.

p, q, r, s, and t in FIG. 17 were the light transmittance in the caseswhere the percentages of titanium dioxide coated mica G and H were100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the transmitted light in thesemitransmissive diffusing film could be obtained with greeninterference color by titanium dioxide coated mica G as shown in p ofFIG. 17 in the case where the percentage of titanium dioxide coated micaG and H was 100:0.

Also, it is understood that the transmitted light in thesemitransmissive diffusing film could be obtained with red interferencecolor by titanium dioxide coated mica H as shown in t of FIG. 17 in thecase where the percentage of titanium dioxide coated mica G and H was0:100.

To the contrary, in the case where the percentage of the titaniumdioxide coated mica G and H was 50:50, it is understood that thetransmitted light of the semitransmissive diffusing film could beobtained with white interference color which was favorably blended bygreen interference color of titanium dioxide coated mica G and redinterference color of titanium dioxide coated mica G as shown in r ofFIG. 17.

According to the semitransmissive diffusing film of this example 2-4,the transmitted light in the diffusing film could be obtained with muchwhiter interference color by using titanium dioxide coated mica G and Hat the percentage of 50:50 in the case where white light was enteredinto the semitransmissive diffusing film, since green interferencecolors of titanium dioxide coated mica G and red interference color oftitanium dioxide coated mica H were favorably blended.

Further, though the transmitted light in the transmissive diffusing filmcould be obtained with much whiter interference color in the case wheretitanium dioxide coated mica G and H were used at the percentages of50:50 as stated above, the transmitted light in the semitransmissivediffusing film could be obtained with satisfactory and nearly whitecolor tone in the cases where titanium dioxide coated mica G and H wereused at the percentages of 25:75 to 75:25 as shown in q and s of FIG.17.

EXAMPLE 2-5

In example 2-5, a substance which was uniformly dispersed titaniumdioxide coated mica I and J (average particle diameter 10 μm to 60 μm,total 2.0 g) in 15 g of acrylic lacquer, was coated on PET film by abarcoater with 200 μm layer thickness with dry state.

In this example 2-5, the titanium dioxide coated mica I was determinedas white titanium dioxide coated mica. Namely, the layer thickness oftitanium dioxide was determined as 40 nm to 60 nm in titanium dioxidecoated mica I.

To the contrary, the layer thickness of titanium dioxide was determinedso as that the reflected light was obtained with yellow interferencecolor in titanium dioxide coated mica J. Namely, the layer thickness oftitanium dioxide was determined as 60 nm to 80 nm in titanium dioxidecoated mica J.

In FIG. 18, a comparison result of light reflectance in the cases wherethe percentages of titanium dioxide coated mica I and J which were usedin the semitransmissive diffusing film of this example 2-5 werevariously changed is shown. These light reflectances are the lightreflectance at the time (when the reflected light from thesemitransmissive diffusing film) was vertically received in thecondition of diffused lighting of white light.

u, v, w, x and y in FIG. 18 were the light reflectance in the case wherethe percentages of the titanium dioxide coated mica I and J were 100:0,75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the reflected light in thesemitransmissive diffusing film could be obtained with liver brown oftitanium dioxide coated mica I as shown in u of FIG. 18 in the casewhere the percentage of titanium dioxide coated mica I and J which wereused in the semitransmissive diffusing film of this example 2-5 was100:0.

Also, it is understood that the reflected light in the semitransmissivediffusing film could be obtained with yellow reflected color of titaniumdioxide coated mica J as shown in y of FIG. 18 in the case where thepercentage of titanium dioxide coated mica I and J was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica I and J was 50:50, it is understood that the reflected lightin the semitransmissive diffusing film could be obtained with muchwhiter interference color which was favorably blended by liver browninterference color of titanium dioxide coated mica I and yellowinterference color of titanium dioxide coated mica J as shown in w ofFIG. 18.

According to the semitransmissive diffusing film of this example 2-5,the reflected light in the semitransmissive diffusing film could beobtained with much whiter interference color by using titanium dioxidecoated mica I and J at the percentage of 50:50 as shown in w of FIG. 18,as compared with u and y which were shown the conventional examples, inthe case where white light was entered to the reflective diffusing film,since liver brown interference color of titanium dioxide coated mica Iand yellow interference color of titanium dioxide coated mica J werefavorably blended.

Further, though the reflected light in the semitransmissive diffusingfilm could be obtained with much whiter interference color in the casewhere titanium dioxide coated mica I and J were used at the percentageof 50:50 as stated above, the reflected light in the semitransmissivediffusing film could be obtained with satisfactory and nearly whitecolor tone in the case where titanium dioxide coated mica I and J wereused at the percentages of 25:75 to 75:25 as shown in v and x of FIG.18.

EXAMPLE 2-6

In example 2-6, a substance which was uniformly dispersed titaniumdioxide coated mica K and L (average particle diameter 10 μm to 60 μm,total 2.0 g) in 15 g of acrylic lacquer, was coated on PET film by abarcoater with 200 μm layer thickness with dry state.

In this example 2-6, the layer thickness of titanium dioxide wasdetermined so as that the reflected light was obtained with redinterference color in titanium dioxide coated mica K. Namely, the layerthickness of titanium dioxide was determined as 80 nm to 100 nm intitanium dioxide coated mica K.

To the contrary, the layer thickness of titanium dioxide was determinedso as that the reflected light was obtained with green interferencecolor in titanium dioxide coated mica L. Namely, the layer thickness oftitanium dioxide was determined as 140 nm to 160 nm in titanium dioxidecoated mica L.

In FIG. 19, a comparison result of light reflectance in the cases wherethe percentages of titanium dioxide coated mica K and L which were usedin the semitransmissive diffusing film of this example 2-6 werevariously changed is shown. These light reflectances are the lightreflectance at the time (when the reflected light from thesemitransmissive diffusing film) was vertically received in thecondition of diffused lighting of white light.

z, I, II, III and IV in FIG. 19 were the light reflectance in the caseswhere the percentages of the titanium dioxide coated mica K and L were100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the reflected light in thesemitransmissive diffusing film could be obtained with red interferencecolor of titanium dioxide coated mica K as shown in z of FIG. 19 in thecase where the percentage of titanium dioxide coated mica K and L usedin the semitransmissive diffusing film of this example 2-6 was 100:0.

Also, it is understood that the reflected light in the semitransmissivediffusing film could be obtained with green interference color oftitanium dioxide coated mica L as shown in IV of FIG. 19 in the casewhere the percentage of titanium dioxide coated mica K and L was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica K and L was 50:50, it is understood that the reflected lightin the semitransmissive diffusing film could be obtained with muchwhiter interference color as a whole, which was favorably blended by redinterference color of titanium dioxide coated mica K and greeninterference color of titanium dioxide coated mica L as shown in II ofFIG. 19.

According to the semitransmissive diffusing film of this example 2-6,the reflected light in the semitransmissive diffusing film could beobtained with much whiter interference color by using titanium dioxidecoated mica K and L at the percentage of 50:50 as shown in II in FIG.19, as compared with z and IV which shows the conventional examples, inthe case where white light was entered into the reflective diffusingfilm, since red interference color of titanium dioxide coated mica K andgreen interference color of the titanium dioxide coated mica L werefavorably blended.

Further, though the reflected light in the semitransmissive diffusingfilm could be obtained with much whiter interference color in the casewhere titanium dioxide coated mica K and L were used at the percentageof 50:50 as stated above, the reflected light in the semitransmissivediffusing film could be obtained with satisfactory and nearly whitecolor tone in the case where titanium dioxide coated mica K and L wereused at the percentages of 25:75 to 75:25 as shown in I and III of FIG.19.

EXAMPLE 2-7

Two blue pearly pigment that displays purple interference color and hasdifferent particle diameter in each other, were added to acrylic resinlacquer. Then, the mixture which was dispersed and mixed by ahomogenizer and was printed on polyethylene terephthalate (PET) so asthat thickness could be 50 μm by screen printing method. Asemitransmissive diffusing film was manufactured by heating andhardening it at 60° C. The obtained semitransmissive diffusing film wasstuck to the reverse side of a normally white mode TN-type liquidcrystal display element (installed so as to cross the polarizing filmeach other) in the state that said pearly pigment layer was set to thetop. A semitransmissive liquid crystal display element was manufacturedby fitting a back lighting unit which was composed of white cold-cathodetube and aluminum reflective film, under the semitransmissive diffusingfilm. According to the obtained semitransmissive liquid crystal displayelement, the design which displays the different color tone according toON and OFF of the back lighting was revealed. For example, displayportion black-non display portion blue, in the case where the backlighting was switched ON and display portion black-non display portionpurple, in the case where the back lighting was switched OFF.

As explained above, according to the semitransmissive diffusing film ofthe present invention, said semitransmissive diffusing film comprisestwo or more of powder which has an interference color. Namely, thetransmitted light or the reflected light at the semitransmissivediffusing film was obtained with the interference color of the desiredcolor tone as a whole, by properly changing the kinds or percentages ofthese powders and by blending the interference colors of these powders.

Therefore, the semitransmissive diffusing film of the present inventionhas high using efficiency of the light in comparison with thesemitransmissive diffusing film which is obtained its color tone byabsorbing the optical component of the specific wavelength to colorpigment or pigment as in conventional. Accordingly, vivid color tone canbe obtained in stable.

Also, the transmitted light or the reflected light of thesemitransmissive diffusing film can be obtained with the interferencecolor of the desired color tone by changing properly the kinds and thepercentages of these powders. Further, the favorable toning of the colortone is facilitated.

Further, the more beautiful color tone can be obtained by using titaniumdioxide coated synthetic mica which is coated titanium dioxide on thesurface of synthetic mica, because the powders used synthetic mica hasmuch less impurities in comparison with the powders used natural mica.

Reflective Diffusing Film

According to the reflective film in accordance with the presentinvention, the reflective film is preferably comprising two or more ofthe powder which has an interference color as stated above. Namely thereflected light at the reflective diffusing film was obtained with theinterference color of the desired color tone as a whole by properlychanging the kinds or the percentages of these powders and by blendingthe interference color of these powders.

Therefore, the reflective diffusing film of the present invention hadhigh using efficiency of the light in comparison with the reflectivediffusing film which was obtained its color tone by absorbing theoptical component of the specific wavelength to color pigment or pigmentas in conventional. Accordingly, vivid color tone can be obtained instable.

Also, the reflected light at the reflective diffusing film can beobtained with the interference color of the desired color tone bysuitably changing the kinds and the percentages of these powders.Further, the favorable toning of the color tone is facilitated.

In said reflective diffusing film, the powder that the interferencecolor is in a complementary relation can be obtained the reflected lightin the reflective diffusing film with satisfactory white interferencecolor in the case where 25% to 75% of one powder is added to the otherpowder.

Also, in said reflective diffusing film, in the case where said powderis set on the substrate, it is preferable that an amount of said powderon the substrate is 0.01 g/m² to 100 g/m². Namely, it becomes difficultto obtain the reflected light at the reflective diffusing film with thedesired color tone in the case where the amount of said powder on thesubstrate is less than 0.01 g/m².

To the contrary, in the case where said powder is set in the substrate,it is preferable that an amount of said powder is 1 wt % to 70 wt % inthe substrate. Namely, it becomes difficult to obtain the lightreflectance of the reflective diffusing film in favorable in the casewhere the amount of said powder in the substrate is less than 1 wt %. Onthe other hand, strength of the reflective diffusing film is extremelydeteriorated in the case where the amount of said powder in thesubstrate is 70 wt % or more.

Also, it is preferable that the reflective diffusing film of the presentinvention which can obtain the reflected light with white interferencecolor is used in a reflective liquid crystal display element ofblack-and-white display. Namely, it is possible to obtain brightness,visibility, high contrast and wide viewing angle by using the reflectivediffusing film.

It is also preferable that the reflective diffusing film of the presentinvention which can obtain the reflected light with the coloredinterference color of the desired color is used in a reflective liquidcrystal display element of two-color display. Namely it is possible toobtain design, brightness, visibility, high contrast and wide viewingangle by using the reflective diffusing film without using such as acolor filter.

Further, it is also preferable that the reflective diffusing film of thepresent invention which can obtain the reflected light with whiteinterference color is used in a reflective liquid crystal displayelement of color display. Namely, it is possible to obtain highreproducibility of color in the color filter, brightness, visibility,high contrast, and wide viewing angle, by using the reflective diffusingfilm, because, for example, the incident light from the reflectivediffusing film to the color filter can be obtained with much whitercolor tone.

Also, a reflective diffusing film in accordance with the presentembodiment can be manufactured by incorporating these powders in asubstrate (nitrocellulose, acrylic polymer, polycarbonate, polyester,polyurethane, polyethylene terephthalate (PET) and the like).

A reflective diffusing film can be manufactured by printing or coatingthe powder on the substrate as an ink.

As for the ink which prepared with said powder, the ink which wasdispersed and mixed said powder into a resin binder such as polyacryl,polyurethane, polycarbonate, polyester and the like can be used.

Also, as for the coating methods, screen printing method, roll coater,offset printing method, knife coater, comma coater, and the like can belisted as an example.

Also, as for the substrate, transparent, semitransparent and whiteplastic sheet (thickness about 10 μm to 1000 μm), and the like can beused. For example, polyolefines such as polyvinyl chloride,polyethylene, polypropylene, and the like, polyesters such aspolyethylene terephthalate and the like, resins such as polystyrene,polycarbonate, acrylic resin, polyurethane resin and the like can beused. Also, it is possible to add 20 wt % to 100 wt % of a plasticizerto the resin as occasion demands. It is also possible to use metallicplates or deposited films such as silver.

Also, surface finishing such as embossing finish and the like can beconducted, as occasion demands.

Further, 1 wt % to 50 wt % of white pigment, transparent particle,plastic bead, and the like can be added with respect to the powder forthe purpose of toning the color tone of the reflected light at thereflective diffusing film.

As for the white pigment, titanium dioxide coated mica which has notinterference color, barium sulfate, titanium dioxide, zinc oxide,magnesium oxide, titanium dioxide, transparent particle, silicaparticle, plastic bead, acryl, nylon, polystyrene, polysilicone and thelike can be listed as an example.

Also, it is preferable that a particle diameters of these powders are0.1 μm to 200 μm.

Further, the more beautiful color tone can be obtained by using titaniumdioxide coated synthetic mica which is coated titanium dioxide on thesurface of synthetic mica as the powder which has characteristicinterference color in the present invention, because the powders usedsynthetic mica has much less impurities in comparison with the powdersused natural mica.

As stated above, according to a reflective liquid crystal displayelement 22 in accordance with the embodiment of the present invention,titanium dioxide coated mica 14a and 14b that each interference color isin a complementary relation, are used in the substrate 17 so as that thereflected light at the reflective diffusing film can be obtained withwhite interference color.

Therefore, the reflective diffusing film of the present invention hadhigh using efficiency of the light in comparison with the reflectivediffusing film which was obtained its color tone by absorbing theoptical component of the specific wavelength to color pigment or pigmentas in conventional. Accordingly, vivid color tone can be obtained instable.

Also, the reflected light at the reflective diffusing film 28 can beobtained with white interference color as a whole, by properly changingthe layer thickness and the percentages of titanium dioxide in titaniumdioxide coated mica 14a and 14b and by favorably blending theinterference color of these titanium dioxide coated mica 14a and 14b.

Also, the reflective diffusing film and the reflective liquid crystaldisplay element using the same in accordance with the present inventionare not limited to these constitutions, and various formations can beadopted within the range of the essentials of the invention.

Also, in the case where said titanium dioxide coated mica 14a and 14bare set on the substrate which have light reflectance, the reflectedlight at the reflective diffusing film can be obtained with the desiredcolor tone by determining the amounts of said powder on the substrate as0.01 g/m² to 100 g/m².

To the contrary, in the case where said titanium dioxide coated mica 14aand 14b are set in the substrate which does not have light reflectance,the light reflectance of the reflective diffusing film can be obtainedin favorable and satisfactory intensity of the reflective diffusing filmcan be obtained in the case where the amounts of said titanium dioxidecoated mica 14a and 14b on the substrate was 1 wt % to 70 wt %.

Also, brightness, visibility, high contrast and wide viewing angle canbe obtained by using the reflective diffusing film in accordance withthe present invention that the reflected light can be obtained withwhite interference color in the reflective liquid crystal displayelement of black-and-white display.

Further, design, brightness, visibility, high contrast, and wide viewingangle can be obtained by using the reflective diffusing film inaccordance with the present invention that the reflected light can beobtained with the colored interference color of the desired color tone,in the reflective liquid crystal display element of two-color display,because, for example, the colored color tone can be obtained withoutusing the color filter.

Also, high reproducibility of color in the color filter, brightness,visibility, high contrast, and wide viewing angle can be obtained byusing the reflective diffusing film in accordance with the presentinvention that the reflected light can be obtained with whiteinterference color in the reflective liquid crystal display element ofcolor display, because, for example, the internal light from thereflective diffusing film to the color filter can be obtained with muchwhiter color tone.

Further, the more beautiful color tone can be obtained in the case wheretitanium dioxide coated synthetic mica which is coated titanium dioxideon the surface of synthetic mica as these titanium dioxide coated mica14a and 14b, since the titanium dioxide coated synthetic mica has muchless impurities as compared with a titanium dioxide coated mica which isused natural mica.

Also, the concrete manufacturing process of the reflective liquidcrystal display element in accordance with the present embodiment willbe shown in the following manufacturing process 3-1.

Manufacturing Process 3-1

First, the powder in accordance with the present invention was added toacrylic resin lacquer. Then, the mixture which was dispersed and mixedby a homogenizer was printed on polyethylene terephthalate (PET) so asthat thickness could be 50 μm by screen printing method. A reflectivediffusing film was manufactured by heating and hardening it at 60° C.

A reflective liquid crystal display element was manufactured by stickingthe obtained reflective diffusing film to the reverse side of a normallywhite mode TN-type liquid crystal display element (installed so as tocross the polarizing film each other) in the state that said powderlayer was set to the top.

In the following the preferable examples of the present invention willbe explained. However, the present invention is not limited to theseexamples.

EXAMPLE 3-1

In example 3-1, a substance which dispersed titanium dioxide coated micaA and B whose interference colors are complementary to each other(average particle diameter 10 μm to 60 μm, total 2.0 g) in 15 g ofacrylic lacquer with 50:50, was coated on PET film by a barcoater withthe layer thickness 200 μm with dry state.

In this example 3-1, the layer thickness of titanium dioxide which wascoated on the surface of mica was determined as about 40 nm to 60 nm intitanium dioxide coated mica A and the layer thickness of titaniumdioxide which was coated on the surface of mica was determined as about60 nm to 80 nm in titanium dioxide coated mica B.

In FIG. 20, a comparison result of light reflectances between the casesthat the reflective diffusing film of this example 3-1 and theconventional reflective diffusing film were used is shown. These lightreflectances are the light reflectance at the time (when the reflectedlight from the reflective diffusing film) was vertically received in thecondition of diffused lighting of white light.

b, c and d in FIG. 20 are the light reflectance of the reflectivediffusing film in accordance with this example 3-1, the reflectivediffusing film which comprised one of general pearly pigment inconventional and the conventional silver deposited film which hasmetallic luster, respectively.

As a result, it is understood that light reflectance was almost flat inthe range of 400 nm to 700 nm in the case where b in FIG. 20 which showsthis example 3-1 was compared with c and d in FIG. 20 which shows theconventional example. In particular, it is also understood that lightreflectance was largely improved in the case where b in FIG. 20 whichshows this example 3-1 was compared with d in FIG. 20 which shows theconventional example.

Namely, according to the reflective diffusing film of this example 3-1,it is possible to obtain the reflected light at the reflected diffusingfilm with the much desired color.

EXAMPLE 3-2

In example 3-2, a substance which was uniformly dispersed titaniumdioxide coated mica C and D (average particle diameter 10 μm to 60 μm,total 2.0 g) in 15 g of acrylic lacquer, was coated on PET film by abarcoater with 200 μm layer thickness with dry state.

In this example 3-2, titanium dioxide coated mica C was determined aswhite titanium dioxide coated mica. Namely, the layer thickness oftitanium dioxide was determined as 40 nm to 60 nm in titanium dioxidecoated mica C.

To the contrary, in titanium dioxide coated mica D, the layer thicknessof titanium dioxide was considered so as that the reflected light couldbe obtained with yellow interference color. Namely, the layer thicknessof titanium dioxide was determined as 60 nm to 80 nm in titanium dioxidecoated mica D.

In FIG. 21, a comparison result of light reflectance in the cases wherethe percentages of titanium dioxide coated mica C and D which were usedin the reflective diffusing film of this example 3-2 were variouslychanged is shown. These light reflectances are the light reflectance atthe time (when the reflected light from the reflective diffusing film)was vertically received in the condition of diffused lighting of whitelight.

e, f, g, h and i in FIG. 21 are the light reflectance in the cases wherethe percentages of titanium dioxide coated mica C and D were 100:0,75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the reflected light in the reflectivediffusing film could be obtained with liver brown of titanium dioxidecoated mica C as shown in e of FIG. 21 in the case where the percentageof titanium dioxide coated mica C and D used in the reflective diffusingfilm in accordance with this example 3-2 was 100:0.

Also, it is understood that the reflected light in the reflectivediffusing film could be obtained with yellow interference color oftitanium dioxide coated mica D as shown in i of FIG. 21 in the casewhere the percentage of titanium dioxide coated mica C and D was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica C and D was 50:50, it is understood that the reflected lightin the reflective diffusing film could be obtained with whiteinterference color as a whole which was favorably blended by liver browninterference color of titanium dioxide coated mica C and yellowinterference color of titanium dioxide coated mica D as shown in g ofFIG. 21.

According to the reflective diffusing film in accordance with thisexample 3-2, the reflected light in the reflective diffusing film couldbe obtained with much whiter interference color by using titaniumdioxide coated mica C and D at the percentage of 50:50 in the case wherewhite light was entered to the reflective diffusing film, because liverbrown interference color of titanium dioxide coated mica C and yellowinterference color of titanium dioxide coated mica D were favorablyblended.

Also, though the reflected light in the reflective diffusing film couldbe obtained with much whiter interference color in the case wheretitanium dioxide coated mica C and D were used at the percentage of50:50 as stated above, the reflected light in the reflective diffusingfilm could be obtained with satisfactory and nearly white color tone inthe case where titanium dioxide coated mica C and D were used at thepercentages of 25:75 to 75:25 as shown in f and h in FIG. 21.

EXAMPLE 3-3

In example 3-3, a substance which was uniformly dispersed titaniumdioxide coated mica E and F (average particle diameter 10 μm to 60 μm,total 2.0 g) in 15 g of acrylic lacquer, was coated on PET film by abarcoater with 200 μm layer thickness with dry state.

In this example 3-3, the layer thickness of titanium dioxide wasconsidered so as that the reflected light could be obtained with redinterference color in titanium dioxide coated mica E. Namely, the layerthickness of titanium dioxide was determined as 80 nm to 100 nm intitanium dioxide coated mica E.

To the contrary, the layer thickness of titanium dioxide was consideredso as that the reflected light could be obtained with green interferencecolor in titanium dioxide coated mica F. Namely, the layer thickness oftitanium dioxide was determined as 140 nm to 160 nm in titanium dioxidecoated mica F.

In FIG. 22, a comparison result of light reflectance in the case wherethe percentages of titanium dioxide coated mica E and F which were usedin the reflective diffusing film of this example 3-3 were variouslychanged is shown. These light reflectances are the light reflectance atthe time (when the reflected light from the reflective diffusing film)was vertically received in the condition of diffused lighting of whitelight.

j, k, l, m and n in FIG. 22 were the light reflectance in the caseswhere the percentages of titanium dioxide coated mica E and F were100:0, 75:25, 50:50, 25:75, 0:100, respectively.

As a result, it is understood that the reflected light in the reflectivediffusing film could be obtained with red interference color of titaniumdioxide coated mica E as shown in j in FIG. 22 in the case where thepercentage of titanium dioxide coated mica E and F used in thereflective diffusing film in accordance with this example 3-3 was 100:0.

Also, it is understood that the reflected light in the reflectivediffusing film could be obtained with green interference color oftitanium dioxide coated mica F as shown in n of FIG. 22 in the casewhere the percentage of titanium dioxide coated mica E and F was 0:100.

To the contrary, in the case where the percentage of titanium dioxidecoated mica E and F was 50:50, it is understood that the reflected lightin the reflective diffusing film could be obtained with whiteinterference color as a whole which was favorably blended by redinterference color of titanium dioxide coated mica E and greeninterference color of titanium dioxide coated mica F as shown in l ofFIG. 22.

According to the reflective diffusing film of this example 3-3, thereflected light in the reflective diffusing film could be obtained withmuch whiter interference color by using titanium dioxide coated mica Eand F at the percentage of 50:50 in the case where white light wasentered into the reflective diffusing film, because red interferencecolor of titanium dioxide coated mica E and green interference color oftitanium dioxide coated mica F were favorably blended.

Also, though the reflected light in the reflective diffusing film couldbe obtained with much whiter interference color in the case wheretitanium dioxide coated mica E and F were used at the percentage of50:50 as stated above, the reflected light in the reflective diffusingfilm could be obtained with satisfactory and nearly white color tone inthe cases where titanium dioxide E and F were used at the percentages of25:75 to 75:25 as shown in k and m of FIG. 22.

As explained above, according to the reflective diffusing film of thepresent invention, the reflective diffusing film comprises two or moreof the powder which has an interference color. Namely, the reflectedlight at the reflective diffusing film can be obtained with theinterference color of the desired color tone as a whole, by properlychanging the kinds or the percentages of these powders and by blendingthe interference color of these powders.

Therefore, the reflective diffusing film of the present invention hadhigh using efficiency of the light in comparison with the reflectivediffusing film which was obtained its color tone by absorbing theoptical component of the specific wavelength to color pigment or pigmentas in conventional. Accordingly, vivid color tone can be obtained instable.

Also, the reflected light of the reflective diffusing film can beobtained with the interference color of the desired color tone bychanging properly the kinds and the percentages of these powders.Further, the favorable toning of the color tone is facilitated.

Further, the more beautiful color tone can be obtained by using titaniumdioxide coated synthetic mica which is coated titanium dioxide on thesurface of synthetic mica, because titanium dioxide coated syntheticmica has much less impurities in comparison with titanium dioxide coatedmica which used natural mica.

Also, brightness, visibility, high contrast and wide viewing angle canbe obtained by using the reflective diffusing film in accordance withthe present invention that the reflected light is obtained with whiteinterference color in the reflective liquid crystal display element ofblack-and-white display.

Further, design, brightness, visibility, high contrast, and wide viewingangle can be obtained by using the reflective diffusing film inaccordance with the present invention that the reflected light isobtained with the colored interference color of the desired color tone,in the reflective liquid crystal display element of two-color display,because, for example, the colored color tone can be obtained withoutusing the color filter.

Also, high reproducibility of color, brightness, visibility, highcontrast, and wide viewing angle can be obtained by using the reflectivediffusing film in accordance with the present invention that thereflected light is obtained with white interference color for thereflective liquid crystal display element of color display, because, forexample, the internal light from the reflective diffusing film to thecolor filter can be obtained with much whiter color tone.

What is claimed is:
 1. A diffusing film comprising two or more of apowder which have an interference color complementary to eachother,wherein an amount of said powder is 0.01 g/m² to 100 g/m² in thecase where said powder is set on a substrate.
 2. A diffusing film as inclaim 1, wherein said powder is a pearly pigment.
 3. A diffusing filmaccording to claim 1, wherein said powder is a titanium oxide coatedpowder which coated titanium dioxide on the surface of mica, and a layerthickness of titanium dioxide which is coated on mica is the layerthickness that the interference color which is the same wave range withthe absorption wave range can be obtained.
 4. A diffusing film accordingto claim 1, wherein an amount of said powder is 1 wt % to 70 wt % in thecase where said powder is set in the substrate.
 5. A diffusing filmcomprising two or more of a powder which have an interference colorcomplementary to each other, wherein a powder that has the interferencecolor which is in a complementary relation with the other powder, wasadded 10% to 90% with respect to the other powder, so as that atransmitted light at said diffusing film can be obtained with whitelight;wherein an amount of said powder is 0.01 g/m₂ to 100 g/m² in thecase where said powder is set on a substrate.
 6. A diffusing film as inclaim 5, wherein said powder is a pearly pigment.
 7. A diffusing filmaccording to claim 5, wherein said powder is a titanium oxide coatedpowder which coated titanium dioxide on the surface of mica, and a layerthickness of titanium dioxide which is coated on mica is the layerthickness that the interference color which is the same wave range withthe absorption wave range can be obtained.
 8. A diffusing film accordingto claim 5, wherein an amount of said powder is 1 wt % to 70 wt % in thecase where said powder is set in the substrate.
 9. A liquid crystaldisplay element comprising:a light source which irradiates a light flux;a diffusing film which comprises two or more of a powder which have aninterference color which are complementary to each other, wherein anamount of said powder is 0.01 g/m₂ to 100 g/m² in the case where saidpowder is set on a substrate; and a liquid crystal panel which controlslight transmittance of the light flux from said diffusing film bychanging a voltage which applies onto a liquid crystal layer.
 10. Adiffusing film as in claim 9, wherein said powder is a pearly pigment.11. A diffusing film according to claim 9, wherein said powder is atitanium oxide coated powder which coated titanium dioxide on thesurface of mica, and a layer thickness of titanium dioxide which iscoated on mica is the layer thickness that the interference color whichis the same wave range with the absorption wave range can be obtained.12. A diffusing film according to claim 9, wherein an amount of saidpowder is 1 wt % to 70 wt % in the case where said powder is set in thesubstrate.